CSS Div image overflow corss browser issue

Each one of these examples uses a floating image inside of a div container that has a background color.
In Firefox the container only grows as far as how much text is in it. In IE it looks fine. I could've sworn that last night I was looking at this on Firefox on a different machine and it looked fine (can't recall the version #).

I included screenshots of what I am seeing below the actual code. I feel like this has alwyas been a hit or miss thing and I come across this problem fairly frequently.

Ready to showcase your work, publish content or promote your business online? With Squarespace’s award-winning templates and 24/7 customer service, getting started is simple. Head to Squarespace.com and use offer code ‘EXPERTS’ to get 10% off your first purchase.

Yeah! That does it. So, no need to float and display:inline. I wasted too much time trying to resolve that on my own. It's definitely a common layout but for some reason I have been unable to find a clear example of it in use.